Plunger Pump

ABSTRACT

A pump system according on one or more aspects of another embodiment of the present disclosure comprises a pair of plunger pumps disposed in a back-to-back assembly having a width that is less than about 102 inches, wherein each pump comprises a zero offset and at least a six inch stroke.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application No. 61/139,552 filed on Dec. 19, 2008.

BACKGROUND

This section provides background information to facilitate a better understanding of the various aspects of the present invention. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.

Oil and gas wells require servicing such as cementing, gravel packing, and acidizing. All of these services require pumps for pumping fluid down the well. The type of pump used normally for these applications is a plunger type. It has a crankshaft mounted in a housing. A plunger has a crosshead that is reciprocally carried in a cylinder perpendicular to the crankshaft. A connecting rod connects each eccentric portion or journal of the crankshaft to the plunger. A typical pump will be a triplex type having three cylinders, three connecting rods, and three journals on the crankshaft. Normally the axis of rotation of the crankshaft will be intersected by the axis of the cylinder. A diesel engine or other prime mover will connect to a gear train for rotating the crankshaft. An example of a common type of a well service pump (e.g., plunger pump) is disclosed in U.S. Pat. No. 2,766,701 to Giraudeau.

Often these pumps will be mounted on a trailer or skid back-to-back. Each pump has an outboard side connected to a manifold with valves for drawing in and pumping fluid acted on by the plunger. The inboard sides will be located next to each other. A separate prime mover or engine will be connected to each of the pumps. The overall width from the one manifold to the other manifold should not exceed roadway requirements (e.g., Department of Transportation) if the pumps are to be trailer mounted, this being about 8½ feet (e.g., 102 inches). To meet these width requirements, some have reduced the size of the pump, for example reducing the pump stroke from six inches to four inches.

It has been known in the past with larger oil field pumps to increase the stroke length by offsetting the crankshaft axis with the cylinder axis. The offset is selected so that during the power or output stroke, the centerline of the crankshaft end of the connecting rod will be located closer to the cylinder axis than the crankshaft axis. Matzner et al. disclose vertically offsetting the cylinder axis from the crankshaft axis in U.S. Pat. No. 5,246,355. It has also been known for the axis of the wrist pin of the connecting rod to be vertically offset from the cylinder axis to achieve the width requirements. An example of a plunger pump having an offset wrist pin is disclosed in U.S. Pat. No. 5,839,888 to Harrison.

There is a continuing desire to improve plunger pumps. There is a still further desire to provide a plunger pump for mounting in a back-to-back application and achieve a desired width restriction.

SUMMARY

According to one or more aspects of the present disclosure, a pump having a stroke length comprises a housing including a cylinder having a cylinder axis and an entrance; a plunger having a crosshead reciprocally disposed in the cylinder, the plunger comprising a power end section having an outside diameter and a fluid end section having an outside diameter that is different from the outside diameter of the power end section; a manifold positioned adjacent to the cylinder for supplying and delivering fluid acted on by the plunger; a crankshaft rotatably mounted in the housing, the crankshaft having crankshaft axis; a connecting rod having a crankshaft end connected to the crankshaft and a connecting rod connected to the crosshead by a wrist pin; a power end seal disposed adjacent to the entrance to the cylinder, wherein the power end section of the plunger is in sealing contact with the power end seal; and a fluid end seal disposed adjacent to a port to the manifold, wherein the fluid end section of the plunger is in sealing contact with the fluid end seal.

A pump system according on one or more aspects of another embodiment of the present disclosure comprises a pair of plunger pumps disposed in a back-to-back assembly having a width that is less than about 102 inches, wherein each pump comprises a zero offset and at least a six inch stroke.

A plunger pump assembly according to one or more aspects of another embodiment of the present disclosure comprises a first pump and a second pump disposed in a back-to-back assembly having a width that is less than about 102 inches; wherein each of the first and the second pump includes: a housing comprising a cylinder having a cylinder axis and an entrance; a plunger having a crosshead reciprocally disposed in the cylinder, the plunger comprising a power end section having an outside diameter and a fluid end section having an outside diameter that is different from the outside diameter of the power end section; a manifold positioned adjacent to the cylinder for supplying and delivering fluid acted on by the plunger; a crankshaft rotatably mounted in the housing, the crankshaft having crankshaft axis; a connecting rod having a crankshaft end connected to the crankshaft and a connecting rod connected to the crosshead by a wrist pin; a power end seal disposed adjacent to the entrance to the cylinder, wherein the power end section of the plunger is in sealing contact with the power end seal; and a fluid end seal disposed adjacent to a port to the manifold, wherein the fluid end section of the plunger is in sealing contact with the fluid end seal.

The foregoing has outlined some of the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of various features may be arbitrarily increased or reduced for clarity of discussion.

FIG. 1 is a schematic view of a pair of compact pumps mounted in a back-to-back assembly according to one or more aspects of the present disclosure.

FIG. 2A is a sectional view of a prior art well service pump depicted at top dead center (“TDC”).

FIG. 2B is a sectional view of a prior art well service pump depicted at bottom dead center (“BDC”).

FIG. 3 is a section view of a plunger pump according to one or more aspects of the present disclosure positioned proximate to bottom dead center.

FIG. 4 is a sectional view of a plunger pump according to one or more aspects of the present disclosure positioned at a random crankshaft position other than TDC or BDC.

FIG. 5 is a section view of a plunger pump according to one or more aspects of the present disclosure positioned proximate to top dead center.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. Moreover, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact.

FIG. 1 is a plan view of a pair of pumps according to one or more aspects of the present disclosure. FIG. 1 depicts a pair of pumps 10 (e.g., plunger pump, well service pump) mounted in a back-to-back application. Pumps 10 are identical pumps although they may be inverted relative to one another. The pumps may be mounted on a platform 12 (e.g., skid, truck bed, trailer, etc.) together with a prime mover to provide a portable self-contained pumping unit. Depicted in FIG. 1, skid 12 is a trailer adapted for connecting with a tractor (e.g., truck). The prime mover may be an electric motor or an internal combustion engine, for example. The output of the prime mover is connected to gear reducer 14. Pumps 10 are depicted as triplex pumps in the depicted embodiment, however, it will be recognized by those skilled in the art with the benefit of the present disclosure that pump 10 may comprise more or fewer plungers.

Pump 10 comprises an output manifold 16 (e.g., fluid end) and a power end 18. In a back-to-back assembly 8 each pump comprises an inboard end 20 and an outboard end 22. In the depicted embodiment, inboard end 20 is the terminal end of power end 18 and outboard end 22 is the terminal end, or edge, of output manifold 16. In the depicted embodiment, outboard manifolds 16 are disposed at the outside lateral edge 24 of platform 12 to facilitate easy access to the manifolds for connection of hoses and the like. Pump 10 is described generally relative to back-to-back assemblies for purposes of describing a common utilization of well service pumps. The back-to-back illustrations further provides for the opportunity to describe one or more aspects that facilitate achieving a compact plunger pump. However, it will be apparent to those skilled in the art with benefit of the present disclosure that embodiments of pump 10 and various aspects of pump 10 are not limited to back-to-back assemblies or for providing a compact plunger pump.

According to one or more aspects of the present disclosure, pumps 10 are compact in size so as to permit the two pumps to be oriented in back-to-back assembly 8 and to legally travel on United States roadways. For example, government regulations often provide vehicle width restrictions. In the depicted example, the width restriction, denoted by “WR”, is the same as the width of platform 12 and is described as 8.5 feet or 102 inches in this embodiment. According to one or more aspects of the present disclosure, back-to-back pump assembly 8 has a width from outboard end 22 of the left pump to the outboard end 22 of the right pump of less than 102 inches. In one embodiment, the width of back-to-back pump assembly 8 is about 101.5 inches. According to one or more aspects of the present disclosure, back-to-back pump assembly 8 comprises a pair of pumps 10 each having a pump stroke of at least six (6) inches. Each pump 10, according to one or more aspects of the present disclosure, has a zero offset (e.g., on-center), for example the crankshaft axis is not offset from the cylinder axis (e.g., the axes are co-planar) and wherein the wrist pin axis is not offset from the cylinder axis (e.g., the axes are co-planar). According to one or more aspects of the present disclosure, pump assembly 8 comprises a pair of compact pumps 10 that each has at least a six inch stroke and a zero offset.

FIGS. 2A and 2B are cut-away views of a prior art well service plunger pump denoted by the numeral 5. Pump 5 is depicted positioned proximate to top dead center (“TDC”) in FIG. 2A and proximate to bottom dead center (“BDC”) in FIG. 2B. Depicted pump 5 may have a zero offset wherein the cylinder axis (e.g., axis of reciprocation), crankshaft axis and wrist pin axis may be aligned.

Pump 5 comprises a crankshaft 26 rotatably mounted in a housing 28. Crankshaft 26 has a crankshaft axis 30 about which crankshaft 26 rotates. Crankshaft 26 is mounted in housing 28 with bearings 32. Bearings 32 are supported on bearing carriers 34 that are stationary interior parts of housing 28. Crankshaft 26 has a journal 36 which is a shaft portion to which connecting rod 38 is attached. A gear train 40 (shown schematically) rotates crankshaft 26.

Connecting rod 38 has a crankshaft end 42 rotatably mounted (e.g., secured) to journal 36. Connecting rod 38 has an opposite or crosshead end 44 that mounts to a wrist pin 46 of a crosshead 48. Crosshead 48 reciprocates within a cylinder 50 that is mounted in housing 28. Wrist pin 46 has a wrist pin axis 52 that is perpendicular to and located on (e.g., co-planar) the cylinder axis 54 (e.g., axis of reciprocation) in the depicted embodiment. U.S. Pat. No. 5,839,888 discloses offsetting wrist pin axis 52 vertically relative to cylinder axis 54 to achieve a compact plunger pump.

Output manifold 16 comprises a suction valve 62 and a discharge valve 60 in fluid communication through first bore 64 (e.g., vertical bore). The first bore 64 is intersected by a crossbore 66 having a port 68. Plunger 56 reciprocates along cylinder axis 54 through a power end seal 70 and a fluid end seal 72. Power end seal 70 is mounted with housing 28 adjacent to the entrance port 84 of cylinder 50 and fluid end seal 72 is located at port 68. Plunger 56 comprises an elongated shared sealing surface 74, also referred to as the wetted region 74. Shared sealing surface 74 contacts each of power end seal 70 and fluid end seal 72. Sealing surface 74 typically comprises a hard, smooth surface which may comprise a material (e.g., coating) mounted or applied to plunger 56 to provide a better mating surface with seals 70, 72. However, over time it is common for surface 74 to deteriorate and degrade seal 70 and/or seal 72 resulting in pumpage from fluid end 16 into power end 18.

FIG. 3 is a sectional schematic of a plunger pump 10 according to one or more aspects of the present disclosure depicting pump 10 and crankshaft 26 at bottom dead center. FIG. 5 depicts plunger pump 10 at top dead center and FIG. 4 depicts crankshaft 26 and pump 10 at a random position between TDC and BDC. Depicted pump 10 has a stroke of six inches and is adapted for mounting in a back-to-back assembly 8, for example to achieve a one-hundred-two width restriction. Pump 10 comprise a zero offset, wherein cylinder axis 54 (e.g., axis of reciprocation), crankshaft 26 axis 30 and wrist pin axis 52 are aligned.

Pump 10 comprises a plunger 76 having a power end section 78 and a fluid end section 80. Referring to FIG. 4, fluid end section 80 has an outside diameter 80D which is smaller, in the depicted embodiment, than the outside diameter 78D of power end section 78. Power end section 78 and fluid end section 80 of plunger 76 may comprise a single piece of material or independent members attached to one another, for example by threading, welding, brazing, etc.

As will be recognized by those skilled in the art with benefit of this disclosure, the different outside diameter sections 78, 80 of plunger 76 provides a physical barrier to the ingress of fluid (e.g., pumpage) from fluid end 16 to power end 18. In other words, the different outside diameters creates a physical barrier between the fluid end seal 72 and power end seal 70 which is not present in the prior art pumps along the seal surface 74 (e.g., wet surface) of the prior plunger 56 depicted in FIGS. 2A and 2B.

In the depicted embodiments, the outside diameter of power end section 78 of plunger 76 is in sealing contact with power end seal 70 such that the outside diameter 78D provides a sealing surface with seal 70 as plunger 76 reciprocates. The length of plunger power end section 78 is about the length of the stroke of pump 10 plus about two times the length of power end seal 70. Thus, in the depicted embodiment, the length of plunger power end section 78 is about 6 inches plus two times the length of power end seal 70 to provide for a full six inch pump stroke. Power end seal 70 extends into power end 18 and away from fluid end 16. For example, power end seal 70 is disposed on seal housing 82 extending into cylinder 50 and power end 18 from entrance port 84 expressly depicted in FIG. 3. Fluid end 58 of crosshead 48 includes a recessed section 58A which is recessed from fluid end 58 toward wrist pin 46 and away from fluid end 16. Plunger power end section 78 is attached to crosshead 48 at recessed section 58A. In this embodiment, recessed section 58A is attached to plunger 76, for example by threading, such that recessed section 58A (e.g., pin end) extends into plunger power end section 78 (e.g., female end).

The length of fluid end section 80 of plunger 76 is proximate to the stroke length of pump 10 plus about two times the length of fluid end seal 72. In the depicted embodiment, the length of plunger fluid end section 80 is about six inches plus two times the length of seal 72. In the depicted embodiment, seal 72 has been recessed into bore 66 (e.g., cross-bore, receiving bore) of fluid end 16 and away from power end 18. Outside diameter 80D of fluid end section 80 forms a sealing surface with plunger end seal 72 as plunger 76 reciprocates.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure. The scope of the invention should be determined only by the language of the claims that follow. The term “comprising” within the claims is intended to mean “including at least” such that the recited listing of elements in a claim are an open group. The terms “a,” “an” and other singular terms are intended to include the plural forms thereof unless specifically excluded. 

1. A pump having a stroke length, the pump comprising; a housing comprising a cylinder having a cylinder axis and an entrance; a plunger having a crosshead reciprocally disposed in the cylinder, the plunger comprising a power end section having an outside diameter and a fluid end section having an outside diameter that is different from the outside diameter of the power end section; a manifold positioned adjacent to the cylinder for supplying and delivering fluid acted on by the plunger; a crankshaft rotatably mounted in the housing, the crankshaft having crankshaft axis; a connecting rod having a crankshaft end connected to the crankshaft and a connecting rod connected to the crosshead by a wrist pin; a power end seal disposed adjacent to the entrance to the cylinder, wherein the power end section of the plunger is in sealing contact with the power end seal; and a fluid end seal disposed adjacent to a port to the manifold, wherein the fluid end section of the plunger is in sealing contact with the fluid end seal.
 2. The pump of claim 1, wherein the outside diameter of the power end section of the plunger is larger than the outside diameter of the fluid end of the plunger.
 3. The pump of claim 1, wherein the cylinder axis and the crankshaft axis are co-planar with an axis of the wrist pin.
 4. The pump of claim 1, wherein the cylinder axis and the crankshaft axis are co-planar.
 5. The pump of claim 1, wherein the cylinder axis is co-planar with an axis of the wrist pin.
 6. The pump of claim 1, wherein the stroke length of the pump is at least about six inches.
 7. The pump of claim 1, wherein the power end section of the plunger comprises a length equal to about the stroke length of the pump plus two times the length of the power end seal.
 8. The pump of claim 1, wherein the fluid end section of the plunger comprises a length equal to about the stroke length of the pump plus two times the length of the fluid end seal.
 9. The pump of claim 1, wherein: the power end section of the plunger comprises a length equal to about the stroke length of the pump plus two times the length of the power end seal; and the fluid end section of the plunger comprises a length equal to about the stroke length of the pump plus two times the length of the fluid end seal.
 10. The pump of claim 9, wherein the stroke length is at least about six inches.
 11. The pump of claim 9, wherein the outside diameter of the power end section of the plunger is larger than the outside diameter of the fluid end of the plunger.
 12. The pump of claim 11, wherein the stroke length is at least about six inches.
 13. The pump of claim 9, wherein the plunger is attached to the crosshead at a recessed portion of a fluid end of the crosshead, wherein the recessed portion is recessed toward the wrist pin relative to the fluid end of the crosshead.
 14. The pump of claim 13, wherein the recessed portion extends into the power end section of the plunger.
 15. A pump system, comprising a pair of plunger pumps disposed in a back-to-back assembly having a width that is less than about 102 inches, wherein each pump comprises a zero offset and at least a six inch stroke.
 16. The pump system of claim 15, wherein each pump of the pair of pumps comprises a plunger comprising a power end section having an outside diameter in sealing contact with a power end seal and a fluid end section having an outside diameter in sealing contact with a fluid end seal, wherein the outside diameter of the power end section is different from the outside diameter of the fluid end section.
 17. A plunger pump assembly, the assembly comprising a first pump and a second pump disposed in a back-to-back assembly having a width that is less than about 102 inches, wherein each of the first and the second pump comprises: a housing comprising a cylinder having a cylinder axis and an entrance; a plunger having a crosshead reciprocally disposed in the cylinder, the plunger comprising a power end section having an outside diameter and a fluid end section having an outside diameter that is different from the outside diameter of the power end section; a manifold positioned adjacent to the cylinder for supplying and delivering fluid acted on by the plunger; a crankshaft rotatably mounted in the housing, the crankshaft having crankshaft axis; a connecting rod having a crankshaft end connected to the crankshaft and a connecting rod connected to the crosshead by a wrist pin; a power end seal disposed adjacent to the entrance to the cylinder, wherein the power end section of the plunger is in sealing contact with the power end seal; and a fluid end seal disposed adjacent to a port to the manifold, wherein the fluid end section of the plunger is in sealing contact with the fluid end seal.
 18. The pump of claim 17, wherein the outside diameter of the power end section of the plunger is larger than the outside diameter of the fluid end of the plunger.
 19. The pump of claim 17, wherein the cylinder axis and the crankshaft axis are co-planar with an axis of the wrist pin.
 20. The pump of claim 17, wherein the cylinder axis and the crankshaft axis are co-planar.
 21. The pump of claim 17, wherein the cylinder axis is co-planar with an axis of the wrist pin.
 22. The pump of claim 17, wherein a stroke length of the pump is at least six inches.
 23. The pump of claim 17, wherein the power end section of the plunger comprises a length equal to about the stroke length of the pump plus two times the length of the power end seal.
 24. The pump of claim 17, wherein the fluid end section of the plunger comprises a length equal to about the stroke length of the pump plus two times the length of the fluid end seal.
 25. The pump of claim 17, wherein: the power end section of the plunger comprises a length equal to about the stroke length of the pump plus two times the length of the power end seal; and the fluid end section of the plunger comprises a length equal to about the stroke length of the pump plus two times the length of the fluid end seal. 